Electronic devices sometimes contain transparent structures. For example, the display in a cellular telephone may be covered with a layer of glass. Cosmetic coatings such as masking layers of black and white ink are sometimes formed on the inner surfaces of the glass layer. In some devices, transparent button members may be coated with ink layers.
If care is not taken, the masking material that is used to coat a transparent structure in an electronic device may be prone to discoloration. For example, white ink layers that contain titanium oxide particles may acquire a bluish tint upon exposure to ultraviolet light.